High density magnetic recording apparatus including a hologram type magnetic head positioning system

Abstract

A magnetic recording apparatus including a magnetic head portion 9, a light emitting portion 10b emitting a light beam, a hologram portion 10a, a light receiving portion 10c, a carriage 12 and a control portion 16 for positioning the magnetic head portion 9 to a predetermined position. The hologram portion 10a is in a plate-like shape and has on one major surface a first gold reflection surface 10a3 formed on a first thing film layer 10a1 and on the other major surface a second gold reflection surface 10a4 formed on a second thin film layer 10a2. The hologram portion 10a also includes a light path 10a5 that guides the light beam in a zig-zag manner between the first and the second reflection surfaces 10a3 and 10a4 and optical components 10a8, 10a9, 10a10 for converting the light emitted from the light emitting portion 10b into a positioning light beam.

What is claimed is: 
     
       1. A magnetic recording apparatus comprising: a magnetic head portion for recording information on a disc-shaped recording medium and reproducing recorded information from said recording medium;   a light emitting portion for emitting light;   a hologram portion for converting said light from said light emitting portion into positioning light for positioning said magnetic head portion and for radiating it onto said recording medium and for receiving the reflected light therefrom;   a light receiving portion for receiving said reflected light through said hologram portion and outputting a received light intensity signal;   a carriage having said magnetic head portion located thereon and arranged so as to be freely movable in a radial direction; and   a control portion for driving said carriage in response to said received light intensity signal from said light receiving portion and being operable to position said magnetic head portion at a predetermined position;   said hologram portion including a body member having first and second major surfaces;   said body member of the hologram portion having a first thin film layer made of a predetermined metal or a composition thereof located on said first major surface and a first reflection surface made of metallic material located on said first thin film layer   said hologram portion having a second thin film layer made of a predetermined metal or a composition thereof located on said second major surface and a second reflection surface made of metallic material located on said second thin film layer; and   said body member of the hologram portion further including a light path for transmitting light therethrough in a zig-zag manner between said first and second reflection surfaces and a plurality of optical means located on said body member and in said light path for converting the light from said light emitting portion into said positioning light.   
     
     
       2. The magnetic recording apparatus as claimed in claim 1, wherein said predetermined metal is titanium and said first and second thin film layers have a film thickness of about 30 Å or less. 
     
     
       3. The magnetic recording apparatus as claimed in claim 2, wherein said first and second thin film layers have a film thickness having a range between about 10-20 Å. 
     
     
       4. The magnetic recording apparatus as claimed in claim 2 wherein said first and second thin film layers have a film thickness of about 10 Å. 
     
     
       5. The magnetic recording apparatus as claimed in claim 2, wherein said first and second thin film layers have a film thickness having a range between about 10-30 Å. 
     
     
       6. The magnetic recording apparatus as claimed in claim 1, wherein said predetermined metal composition is titanium oxide and said first and second thin film layers have a film thickness of about 30 Å or less. 
     
     
       7. The magnetic recording apparatus as claimed in claim 6, wherein said first and second thin film layers have a film thickness having a range between about 10-20 Å. 
     
     
       8. The magnetic recording apparatus as claimed in claim 6, wherein said first and second thin film layers have a film thickness of about 10 Å. 
     
     
       9. The magnetic recording apparatus as claimed in claim 6, wherein said first and second thin film layers have a film thickness having a range between about 10-30 Å. 
     
     
       10. The magnetic recording apparatus as claimed in claim 1, wherein said predetermined metal is chromium and said first and second thin film layers have a film thickness of about 30 Å or less. 
     
     
       11. The magnetic recording apparatus as claimed in claim 10, wherein said first and second thin film layers have film thickness having a range between about 10-20 Å. 
     
     
       12. The magnetic recording apparatus as claimed in claim 10, wherein said first and second thin film layers have a film thickness of about 10 Å. 
     
     
       13. The magnetic recording apparatus as claimed in claim 10, wherein said first and second thin film layers have a film thickness having a range between about 10-30 Å. 
     
     
       14. The magnetic recording apparatus as claimed in claim 1, wherein said hologram portion further includes first optical refraction means for dividing the light from said light emitting portion into a plurality of light beams, second optical refraction means for deflecting the travel path of the light passing through the light path, and optical focusing means for focusing the light passing through said light path. 
     
     
       15. The magnetic recording apparatus as claimed in claim 14, wherein said light emitting portion, said hologram portion and said light receiving portion are secured together to define a unitary optical portion assembly supported by said magnetic head portion, said optical portion assembly allowing said positioning light from said hologram portion to be irradiated onto said recording medium through a light passing portion of said magnetic head portion. 
     
     
       16. The magnetic recording apparatus as claimed in claim 15, wherein said hologram portion comprises a first input/output surface disposed at a first predetermined angle with respect to said first reflection surface for introducing the light from said light emitting portion into said first optical refraction means and a second input/output surface disposed at a second predetermined angle with respect to said second reflection surface for projecting the positioning light at light angles onto a position detection track of said recording medium. 
     
     
       17. The magnetic recording apparatus as claimed in claim 16, wherein said optical portion assembly includes a focus position adjusting portion for positioning said hologram portion such that the positioning light focuses on said position detection track of said recording medium. 
     
     
       18. The magnetic recording apparatus as claimed in claim 14 wherein said first optical refraction means comprises a diffraction grating for generating said plurality of light beams, said second refraction means comprises a beam splitter for inputting a power reflected light out of said plurality of light beams to said optical focusing means, and wherein said focusing means comprises a reflection type Fresnel lens for outputting first-power diffraction light out of said plurality of light beams from said recording medium. 
     
     
       19. The magnetic recording apparatus as claimed in claim 1 wherein said metallic material of said first and second reflection surfaces comprises gold. 
     
     
       20. The magnetic recording apparatus as claimed in claim 19 wherein said first and second reflection surfaces have a thickness of about 2000 Å. 
     
     
       21. The magnetic recording apparatus as claimed in claim 1 wherein said light emitting portion includes a laser diode. 
     
     
       22. The magnetic recording apparatus as claimed in claim 21 wherein said laser diode emits a light having a wavelength of about 8000 Å. 
     
     
       23. The magnetic recording apparatus as claimed in claim 21 wherein said light receiving portion includes a photo diode. 
     
     
       24. A magnetic recording apparatus comprising: a magnetic head for recording information on a disc-shaped recording medium and reproducing recorded information from said recording medium;   a light emitting element for emitting light;   hologram means for converting said light from said light emitting element into light for positioning said magnetic head over the recording medium and for radiating it onto said recording medium and for receiving the light reflected therefrom;   a light receiving element for receiving said reflected light through said hologram means and outputting a received light signal;   said hologram means including a body member having first and second major surfaces and a first thin film layer made of a predetermined metal or a composition thereof located on said first major surface and a first reflection surface comprised of gold on said first thin film layer, a second thin film layer made of a predetermined metal or a composition thereof located on said second major surface and a second reflection surface also comprised of gold on said second thin film layers; and   said body member further including a light path for transmitting light therethrough in a zig-zag manner between said first and second reflection surfaces and a plurality of optical means located on said body member and in said light path for converting the light from said light emitting portion into said positioning light.